“These data are quite exciting, as they represent the continued evolution and maturation of how we can potentially utilize exosomes to derive critical molecular information about cancer with the end goal of improving treatment and outcomes for patients,” said Keith Flaherty, M.D., Director, Henri and Belinda Termeer Center for Targeted Therapies at the Massachusetts General Hospital (MGH) Cancer Center in Boston, Mass., and a co-author of the abstract. “The ability of Exosome Diagnostics’ platform to pinpoint tumor-specific gene changes associated with immunotherapy treatment responses in exosomes is a key advancement. I look forward to the continued analysis and potentially incorporation of this method for future diagnostic applications.”

These data build on findings Exosome Diagnostics presented in September 2015 demonstrating the ability of its exoRNA technology to predict early response to immunotherapy treatment two to four weeks after treatment initiation based on mRNA expression changes in plasma. These earlier data also showed the ability of the company’s technology to serially and longitudinally monitor response to immunotherapy treatment in patients with metastatic melanoma. When the exclusion method was applied to plasma samples collected from the same patients, removal of non-tumor exosomes increased the ability to discern early exosome mRNA changes associated with improved progression-free survival (PFS).

“The exclusion method that we have developed addresses a recurring issue with background gene expression that masks tumor-specific gene changes in response to a disease or treatment,” said Vince O’Neill, M.D., Chief Medical Officer of Exosome Diagnostics. “With the ability to remove non-tumor exosomes from plasma, our technology will allow for the efficient enrichment of a cancer-specific exosome signature. We’re continuing our development program for this clinical application with the goal of delivering future diagnostics that can improve the use of immunotherapies and help better inform treatment approaches for patients with metastatic melanoma and other cancers.”

About the Study

In the study, exosomal RNA was isolated from the plasma of sixteen patients with metastatic melanoma before receiving immunotherapy treatment with ipilimumab and longitudinally throughout treatment. Patients were split into two groups, based upon their response to immunotherapy treatment (seven patients achieved progression-free survival, or PFS, of at least six months from the start of treatment and 10 patients had progressive disease). Plasma was collected pre-treatment (baseline) and the first post-treatment time point (week two or week four). Using an exclusion method targeting exosome proteins to remove non-tumor exosomes from plasma, the plasma exosome mRNA signature expression changes were compared with that of total plasma exosome mRNA from the same patient samples.

More than 580 genes were examined across all samples and time points. The exclusion platform identified 10 genes that were significantly increased between pre- and post-treatment time points in the majority of patients who went on to achieve PFS of 6 months and decreased in patients with progressive disease. In contrast, the exosome mRNA signature without the exclusion platform did not identify any gene changes between pre- and post-treatment time points.

Overall, these data demonstrate that Exosome Diagnostics’ platform, when incorporating the exclusion method to remove normal exosomes from plasma, enriches the RNA profile compared to total exosome profiling, leading to more precise and predictive information about patients’ responses to immunotherapy treatment.

About Exosome Diagnostics

Exosome Diagnostics is a privately held company focused on developing and commercializing revolutionary, biofluid-based diagnostics to deliver personalized precision healthcare that improves lives. The company’s novel exosome-based technology platform can yield comprehensive and dynamic molecular insights to transform how cancer and other serious diseases are detected, diagnosed, treated and monitored. Visit www.exosomedx.com to learn more.